Liquid immersed electric circuit interrupter



July 7, 1936,

D. R. DAVIES LIQUID IMMERSEDELECTRIC CIRCUIT INTERRUPTER Filed Jan. 11,1934 Ihvgntor: Dayid R 8 50.135, ti so'r'n'eg. I

Patented July 7, 1936" UNITED I STA-res 2,947,008 uqum nunmnsnn nmc'mrccracurr m'raannr'rsn David Reginald Davies, Didsbnry, England, assignorto General Electric Company, a corporation of New York AppliealtifnJanuary 11, i934, Serial No. 706,193

Great Britain January 24, 1933 3 Claims. (Cl. 200-150) This inventionrelates generally to liquid immersed circuit interrupters, that is tosay circuit interrupters in which the contacts between which the circuitis interrupted are immersed in insulating liquid such as oil for thepurpose of extinguishing arcing at the contacts incidental tointerruption of the circuit, and relates particularly to circuitinterrupters of the kind in which means is provided for setting up amagnetic field to act on the arc so as toassist the insulating liquid inextinguishing the. are.

A principal object of my invention is the provision of an improvedcircuit interrupter of the aforesaid type which shall be eiiicient andpositive in its interrupting action and simple in construction.

According to the present invention, a liquid immersed circuitinterrupter is provided with a coil connected in series with the arccontacts and mounted on a part of the circuit interrupter carryingthe-moving contact so as to be adjacent t0,'and have its magnetic axisdisposed trans? versely of, the path of movement of the moving contact,and therefore of the arc itself, whereby a component of forcedue to thecombined magnetic field set up by the coil current and the arc currentacts on the are substantially at rightangles to the path thereof tendingto move the arc bodily away from the circuit interrupter contacts. 7

Conveniently, in the case of a circuit breaker of the double-break typein which the moving contacts are provided at the ends of a bridgingmember, the coil may be located on, or preferably be wound upon, saidbridging member, and connected between the said contacts. If desired,said bridging member. may be provided with a magnetic core or may beformed in part of magnetic material thereby to have the effect ofconcentrating or directing the magnetic field set up by the coil whenenergized.

The invention may be applied with advantage in connection with liquidimmersed circuit interrupters having provision for supplying to the arecontact. In such application the circuit inter--. i5

rupter will be arranged so that the blast of liquid and/or gas acts toassist the said component of force due to the magnetic field set up asaforesaid,

' in blowing out the are.

In another construction of liquid immersed l0 circuit. interrupteraccording to the invention the moving contact is arranged duringtheopening of the circuit interrupter to move through a passage fromwhich one or more transverse passages extend in the direction ofmovement of the are caused by the aforesaid magnetic field, saidtransverse passages being preferably designed to permit the escape ofthe arc gases turbulently into the ambient liquid.

My invention will be more fully set forth in the in followingdescription referring to the-accompanying drawing. and the features ofnovelty which characterize my invention will be pointed out withparticularity in the claims annexed to and forming a part of thisspecification.

Referring to the drawing, Figure 1 is an elevational view, partly insection, of -a double-break circuit interrupter constructed inaccordance with the invention. v

Fig. 2 is a combined view to an enlarged scale, showing in plan thebridging member of the circuit interrupter illustrated in Fig. l and insection one form of arc extinguishing structure which is associated withthe stationary contacts of the circuit interrupter. 35 Fig. 3.is anexplanatorydiagram to indicate the forces acting on the arc due to themagnetic fields set up.

Fig. 4 is an eievatiornal view of a portion of one form of arcextinguishing structure associated with the stationary contacts of thecircuit interrupter, and

Fig. 5 is a plan view showing the form of a plate or grid constitutingpart of the arc extinguishing structure illustrated in Fig. 4, the form45 of another grid constituting part of the arc moved into and out ofengagement with their respectively associated stationary contacts 4member 8 and are provided with biasing springs H and I2 respectively,for controlling the pressure between said contacts and theirco-operatingstationary contacts. A body of oil or other insulatingliquid designated I3, is maintained in the circuit interrupter tank orhousing I at a level completely to submerge the contacts. To assist inthe extinction of the arc the stationary contacts 4 and 5 are providedwith are extinguishing structures I 4 and I5 respectively, which aremore fullyreferred to hereinafter.

As represented in Fig. 2, the bridging member 8 comprises two spacedinsulating members l8 and I9 which serve to support the hinged contacts6 and 1 respectively, and an insulating tubular member 20, to which saidmembers i8 and I3 are secured. On the member 20 there is wound a coil orhelix 2| of good electrically .conducting material and this coil iselectrically connected at its ends with the moving contacts 6 and 1respectively. As thus arranged, the coil 2| will have, its magnetic axisdisposed transversely of the path of movement of the contacts 6 and 1.

moving contact 1 is dissociated from the stationary contact 5 flows inthe direction towards the contact 5 as indicated by the arrow head 23, amagnetic field will be set up acting in the direction indicated by thearrow 24. The magnetic field established in the vicinity of the are atthe contact 6 by the arc current will act in a clockwise direction asindicated by the arrows at 25 and the magnetic field set up in thevicinity of the are at the contact 1 by the arc current will act incounter-clockwise direction as indicated by the arrows 26. The combinedmagnetic field in the region of the contact 6 due, on the one hand tothe coil current and on the other ,hand to the arc current, will have acomponent acting at right angles to the path of the are as indicated bythe arrow 2]. Similarly the combined magnetic field in the region of thecontact 1, due to the current in the coil 2| and the arc current willhave a component acting at rightangles to the path of the are asindicated by the arrow 28. With this arrangement the longitudinal axisof the coil 2| may be considered as being substantially in a plane withthe longitudinal axis of the arc.

Accordingly the arc at the contact 6 will tend to move bodily away fromthe contacts 4 and 6 in the direction indicated by the arrow 21 and theare at the contact I will tend to move bodily away from the contacts 5and 1 in the directionindicated by the arrow 28.

Each of the arc extinguishing structures I4 and i5 (Fig. 1)associatedwith the stationary contacts 4 and 5 may conveniently be intheform illustrated and describedin the aforesaid United States patent andapplication.

In practice, these structures willbe arranged.

so that the transverse passages (designated 13 in supported from thewall of the circuit breaker- .housing 1, whereby the contacts 6 and Ican be the aforesaid United States Patent No. 1,902,507 and designated 6and I5 in the aforesaid United States application Serial No. 622,780)through which a blast of liquid is caused to pass during the openingmovement of the moving contact, extend in the direction along which thearc tends to move under the action of the forces set up as aforesaid,and in the same sense. Thus the blast of liquid which isdirected on theare at each moving contact will act to assist in moving the arc bodilyaway from the circuit interrupter contacts into the surrounding body ofliquid in which the contacts areimmersed.

In another form of the'arc extinguishing structures I4 and I5, which isillustrated in Figs. 2, 4, and 5, the structure comprises a nest of flatgrids or plates 30, .3! (Fig. 4) oi refractory insulating materialarranged alternately in parallel planes and secured together bysupporting rods 32 which will be adapted to be secured to the stationarycontact with which the structure is to be associated. In theconstruction illustrated in Fig. 2, the grid comprises two fiat plates33 and 34, as shown, the plate 33 is formed with a recess 35 and bothplates 33 and 34 recessed jointly to provide a substantially-circularopening 36 communicating on the one hand with the opening 35 through arestriction 3l and on the other .hand through a further restriction 38with a flared opening 39.

As shown in Fig. 5, the plate 3| is formed with a. recess ofsubstantially the same shape as the recess 35 in the plate 30. In theassembled structure, the grids 30 and 3! are mounted on the supportingrods .32 with the several recesses 35 aligned with the recesses 40 so asto form an extended'passage along which the moving contact will moveduring the opening and closing of the circuit interrupter. This passagewill communicate with a series of shorter parallel passages formed bythe aligned openings 36, throughvtransverse passages formed bytherestricted openings .3'I,and'-the said shorter passages willcomniunicate with the flared openings 39 through transverse passagesformed by the restricted openings 38. I

By this construction a. plurality of passages disposed transversely ofthe direction of movement of the moving contact, and therebytransversely of the path 01. the arc, is provided along which the arcgases will be caused to pass out of the structure and into the ambientliquid under the action of aforesaid magnetic fields. The shaping of thegrids to form restrictions as described will produce turbulence andliquid blast effects tending to increase the efiiciency of the arcextinguishing means.

It should be understood that my invention is not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of my invention.

1. A liquid immersed circuit interrupter comprising a pair oi'stationarycontacts, a vertically movable bridging member arranged to interconnectsaid contacts, a coil carried by said bridging member and electricallyconnected to contact portions at opposite ends thereof so as toconstitute thebridging conductor, the longitudinal axis of said coilextending transversely of the path of movement of said bridging memberand of the arcs formed between said stationary con-. tacts and theaforesaid coacting contact portions.

ammo:

2. A liquid immersed cimuit interrupter com prising stationary contactstructure. coacting movable contact structure, said stationary contactstructure iorming a confining passage through which the arc is drawn'and communi eating pressure exhaust passages disposed transverselythereof, and a coil carried by said movable contact structin-e and inthe circult to be interrupted for producing a magnetic field, said coilarranged so that the resultant force component produced by the reactingmagnetic fields 01' the coil and are currents tends tomgesaidarctromsaidcontiningpassage through said exhaust passage.

8. A liquid immersed circuit interrupter com-:

prising stationary contact structure, coacting movable contactstructure. said stationary structure forming an arc passage throughwhich the arc is drawn and communicating pressure exhaust passagesleading laterally from said are passage. and electromagnetic meansconnected in the circuit to be interrupted coacting with said contactstructure arranged so that the resultant force component produced by thereacting magnetic fields of said electromagnetic means and the arccurrents respectively tends to urge the are from said are passage in alateral direction through said exhaust passage in accordance withprogressive opening movement or said contact structure.

DAVID vREGINALD DAVIES.

